In the past 25 years, the principal investigators have amassed three bodies of longitudinal data on the development of aggression in children. One includes three waves of data spanning three years on over 700 children ages 6 to 11 in the midwestern United States; another includes comparable data on over 1300 children of about the same ages in five other countries (Australia, Finland, Israel, The Netherlands and Poland). The third consists of three waves of data spanning 22 years on over 600 children in the eastern United States. The separate analyses of each body of data have confirmed that aggression is a stable predictive characteristic. These analyses have implicated a number of constitutional, cognitive, familial and environmental variables as precursors of aggression. However, the complex types of interrelations that are suggested by these data are not easily disentangled by univariate or even multivariate techniques involving limited numbers of variables. Rather one needs to test more comprehensive models postulating causal and process relations among a large set of variables. The availability of longitudinal data collected in 6 different cultural settings with comparable methodologies and within one culture (USA) over two different but overlapping time periods (1960-1981) and 1977-a979) provides a unique opportunity for this approach. It is the aim of this proposal to integrate the findings of these 7 longitudinal studies into a comprehensive explanation of the development of aggression in children. Such a theory will specify the structural relations within the entire set of relevant variables with structural equations and will specify the psychological processes that the structural coefficients reflect. With such a theory, children who are highly at risk for antisocial aggression may be identified at an early age and the processes that must be short circuited for prevention will be indicated.